Elastic polyetherester nonwoven web

ABSTRACT

An elastomeric nonwoven web is formed by meltblowing fibers composed of a polyetherester. Nonelastic fibers and/or particulate materials may also be included in the web.

FIELD OF THE INVENTION

The present invention is generally directed to fiber formation and, inparticular, to fibers which may be formed into nonwoven webs and thenonwoven webs formed therefrom.

BACKGROUND OF THE INVENTION

In the field of nonwoven materials, there has been a continuing need formaterials having a high degree of flexibility and elasticity and whichmay be manufactured at a low cost. This need has persisted in spite ofthe fact that such materials could readily be utilized to manufacture awide variety of garments of both the disposable type, such as disposablediapers, or the nondisposable type, such as pants, dresses, blouses andsporting wear, for example, sweatsuits. Further, such materials couldalso be utilized in, for example, upholstery, drapery, liner andinsulation applications. The traits of flexibility and elasticity areparticularly useful characteristics in materials for use in these areasbecause they permit articles manufactured from such materials to closelyconform to the body of the wearer or any item, such as a fixed frame,around which the materials may be wrapped. Additionally, the need for anabsorbent nonwoven elastic material has been recognized because such amaterial could be utilized to manufacture a great disparity of itemswhich have improved absorbency performance as a result of the item'sability to closely conform to a body portion or to some other item whichneeds to be wrapped in an absorbent material. For example, such amaterial could be readily utilized in the areas of feminine hygiene orwound dressing.

While the above-discussed combination of characteristics has been a goalof those of skill in the field of nonwoven materials, the priorcommercial materials known to us are believed to be lacking orinsufficient in one or more of the above-discussed desiredcharacteristics. For example, one group of materials which has beenavailable to those in treating injuries are the so-called "elasticbandages", an example of which is an elastic bandage which iscommercially available from the 3M Company of Minneapolis, Minn. underthe trade designation "Ace Bandage". Elastic bandages of this type aregenerally effective in somewhat immobilizing an injured area. However,such elastic bandages generally have a poor ability to absorb bodilyfluids exuding from the wound.

Another material for similar uses appears in U.K. Pat. No. 1,575,830 toJohnson and Johnson which relates to flexible and absorbent dressingsincluding diapers, surgical dressings, first aid dressings, catamenialdressings and the like. This patent further appears to relate todressings which include an absorbent layer laminated to a plasticbacking film. The backing film is stated to be elastic and easilystretchable, as well as highly flexible. The elastic backing film may beformed from a blend of materials which contains (a) a major portion oflinear or radial A-B-A block copolymers or mixtures of linear or radialA-B-A block copolymers with A-B block copolymers and (b) a resincomponent. It is stated that the A-blocks of the block copolymers may bederived from styrene or styrene homologs and that the B-blocks may bederived from conjugated dienes or lower alkenes and the resin componentmay typically include a major portion of a lower molecular weight resinadapted to associate principally with the thermoplastic A-blocks of theblock copolymers. It should be noted that this patent deals with anelastic film as opposed to an elastic nonwoven web.

U.S. Pat. No. 4,426,417 to Meitner appears to disclose a matrix ofnonwoven fibers which can be used as a wiper with the matrix including ameltblown web having a blend of staple fibers which is a mixture ofsynthetic and cotton fibers blended therein. The wipers may be formed bya meltblowing process by extruding thermoplastic polymers as filamentsinto an air stream which draws and attenuates the filaments into finefibers of an average diameter of up to about ten microns. The staplefiber mixture of synthetic and cotton fibers may be added to the airstream so that the turbulence produced by the air stream results in auniform integration of the staple fiber mixture into the meltblown web.The meltblown fiber component of the matrix may be formed from anythermoplastic composition capable of extrusion into microfibers. It isstated that examples of such compositions include polyolefins, such aspolypropylene and polyethylene, polyesters, such as polyethyleneterephthalate, polyamides, such as nylon, as well as copolymers andblends of these and other thermoplastic polymers. The synthetic staplefiber component of the matrix may be selected from the samethermoplastic materials with polyester being preferred. The cottoncomponent includes staple length cotton fibers of average lengthgenerally in the range of from about one quarter inch to three quarterinch and denier from about one to one and one half. It is stated thatthe process for making the material includes compacting the matrix on aforming drum and then directing it over a feed roll and between apatterned roll and an anvil roll where it is pattern bonded. Theparticular bond pattern is preferably selected to impart favorabletextile-like tactile properties while providing strength and durability.

U.S. Pat. No. 4,426,420 to Likhyani appears to disclose a spunlacedfabric which may be made by the hydraulic entanglement of hard fibers(i.e., fibers generally having low stretch characteristics) andpotentially elastomeric fibers (fibers capable of elongation by at leastone hundred percent before breaking and which are capable of exhibitingelastic characteristics after having been subjected to heat treatment).After hydraulic entanglement of the two types of fibers, the fabric isheat treated to develop the elastic characteristics in the elastomericfibers. It is stated that the hard fibers may be of any syntheticfiber-forming material, such as polyesters, polyamides, acrylic polymersand copolymers, vinyl polymers, cellulose derivatives, glass, and thelike, as well as any natural fiber such as cotton, wool, silk, paper andthe like, or a blend of two or more hard fibers. A representative classof potentially elastic fibers is stated to include polyetheresters andmore specifically, poly(butyleneterephthalate)-co-poly(tetramethyleneoxy) terephthalates.

U.S. Pat. No. 4,100,324 to Anderson et al appears to disclose a nonwovenfabric-like material including an air-formed matrix of thermoplasticpolymer microfibers and a multiplicity of individualized wood pulpfibers or staple fibers such as high crimped nylon fibers. It is statedthat many useful thermoplastic polymers, polyolefins such aspolypropylene and polyethylene, polyamides, polyesters such aspolyethylene terephthalate, and thermoplastic elastomers such aspolyurethanes are anticipated to find the most widespread use in thepreparation of the materials of the '324 patent.

U.S. Pat. No. 3,700,545 to Matsui appears to disclose a syntheticmulti-segmented fiber which includes at least ten segments composed ofat least one component of fiber-forming linear polyamide and polyesterextending substantially continuously along the longitudinal direction ofthe fiber and occupying at least a part of the periphery of the unitarymulti-segmented fiber. These fibers may be produced by spinning amulti-segment spinning material having a cross-section of grainy,nebulous or archipelagic structure.

U.S. Pat. No. 3,594,266 to Okazaki appears to disclose melt spinning ofa sheath/core bicomponent fiber where one component is a polyamide andthe other component is a block-copolyether amide. Okazaki also discussesmeltspinning of a sheath/core bicomponent fiber having a first componentof a blend of polyamide and a copolyetheramide and a second component ofNylon 6. It is stated that the latter material has 34 percentelongation.

DEFINITIONS

The term "elastic" is used herein to mean any material which, uponapplication of a biasing force, is stretchable to a stretched, biasedlength which is at least about 125 percent, that is at least about oneand one quarter, of its relaxed, unbiased length, and which will recoverat least about 40 percent of its stretch or elongation upon release ofthe stretching, elongating force. A hypothetical example which wouldsatisfy this definition of an elastic or elastomeric material would be aone (1) inch sample of a material which is elongatable to at least 1.25inches and which, upon being elongated to 1.25 inches and released, willreturn to a length of not more than 1.15 inches. Many elastic materialsmay be stretched by much more than 25 percent of their relaxed length,for example 100 percent, or more, and many of these will return tosubstantially their original relaxed length, for example, to within 105percent of their original relaxed length upon release of the stretching,elongating force.

As used herein the term "nonelastic" is intended to include any materialnot encompassed by the above definition of the term "elastic".

As used herein the term "microfibers" means small diameter fibers havingan average diameter not greater than about 100 microns, preferablyhaving a diameter of from about 0.5 microns to about 50 microns, morepreferably having an average diameter of from about 4 microns to about40 microns.

As used herein the term "meltblown fibers" means fibers formed byextruding a molten thermoplastic material through a plurality of fine,usually circular, die capillaries as molten threads or filaments into ahigh velocity gas (e.g. air) stream which attenuates the filaments ofmolten thermoplastic material to reduce their diameter. Thereafter, themeltblown fibers are carried by the high velocity gas stream and aredeposited on a collecting surface to form a web of randomly disbursedmeltblown microfibers. Such a process is disclosed, for example, in U.S.Pat. No. 3,849,241 to Buntin and the disclosure of this patent is herebyincorporated by reference.

As used herein the term "nonwoven" includes any web of material whichhas been formed without the use of a weaving. process which produces astructure of individual fibers which are interwoven in an identifiablerepeating manner. Specific examples of nonwoven webs would include,without limitation, a meltblown nonwoven web, a spunbonded nonwoven weband a carded web. Nonwoven webs generally have an average basis weightof from about 5 grams per square meter to about 300 grams per squaremeter. More particularly, the nonwoven webs of the present invention mayhave an average basis weight of from about 10 grams per square meter toabout 120 grams per square meter.

As used herein the term "polyetherester" refers to any material havingthe general formula of: ##STR1## where "G" is selected from the groupincluding poly(oxyethylene)-alpha,omega-diolpoly(oxypropylene)-alpha,omega-diol orpoly(oxytetramethylene)-alpha,omega-diol and

"m", "n" and "a" are positive integers. For example, "a" may be 2, 4 or6.

As used herein the term "absorbent fiber" means any fiber which iscapable of absorbing at least 100 percent of its weight of a fluid.

As used herein the term "superabsorbent fiber" means any fiber which iscapable of absorbing at least 400 percent of its weight of a fluid.

Unless herein specifically set forth and defined or otherwise limited,the term polymer generally includes, but is not limited to,homopolymers, copolymers, such as, for example, block, graft, random andalternating copolymers, terpolymers, etc. and blends and modificationsthereof. Furthermore, unless otherwise specifically limited, the termpolymer shall include all possible geometrical configurations of thematerial. These configurations include, but are not limited to,isotactic, syndiotactic and random symmetries and, for example, linearand radial polymers.

As used herein the term "consisting essentially of" does not exclude thepresence of additional materials which do not significantly affect theproperties of a given material. Exemplary additional materials of thissort would include, without limitation, pigments, anti-oxidants,stabilizers, waxes, flow promoters, solvents, plasticizers, particulatesand materials added to enhance the processability of the material.

OBJECTS OF THE INVENTION

Accordingly, it is a general object of the present invention to provideelastic fibers formed from a polyetherester.

Another general object of the present invention is to provide an elasticnonwoven web which is composed of a coherent nonwoven matrix of elasticfibers formed from a polyetherester.

Yet another general object of the present invention is to provide anelastic nonwoven web which is composed of a coherent nonwoven matrix ofelastic fibers formed from a polyetherester with at least one other typeof fiber being distributed within or on the matrix.

A further object of the present invention is to provide an elasticabsorbent nonwoven web which is composed of a coherent nonwoven matrixof elastic fibers formed from a polyetherester with at least one type ofabsorbent fiber being distributed within or on the matrix.

Still further objects and the broad scope of applicability of thepresent invention will become apparent to those of skill in the art fromthe details given hereinafter. However, it should be understood that thedetailed description of the presently preferred embodiment given hereinof the present invention is given only by way of illustration becausevarious changes and modifications well within the spirit and scope ofthe invention will become apparent to those of skill in the art in viewof this detailed description.

SUMMARY OF THE INVENTION

The present invention provides elastic meltblown fibers formed from apolyetherester. The elastic meltblown fibers may be formed into anelastic nonwoven web which includes a coherent nonwoven matrix of fiberswhich, for example, may be microfibers. The elastic nonwoven web mayalso include at least one type of secondary fibers, for examplesecondary microfibers, which are distributed within or upon the matrix.The secondary fibers may be generally uniformly distributed throughoutthe matrix.

The elastic fibers are formed from a polyetherester material having theformula: ##STR2## where "G" is selected from the group including:poly(oxyethylene)-alpha,omega-diol poly(oxypropylene)-alpha,omega-diolpoly(oxytetramethylene)-alpha,omega-diol and

"a", "m" and "n" are positive integers. For example, "a" may be 2, 4 or6.

In particular, the polyetherester has a density of from about 1.10 toabout 1.18 when measured in accordance with ASTM D-792; a melt point offrom about 350° F. to about 400° F. when measured in accordance withASTM D-2117; a tensile strength of from about 2,250 psi to about 3,250psi when measured in accordance with ASTM D-638; an elongation at breakof from about 600 percent to about 750 percent when measured inaccordance with ASTM D-638; a flexural modulus of from about 6,500 psito about 15,000 psi when measured in accordance with ASTM D-790 and amoisture absorption (at equilibrium, room temperature and 50 percentrelative humidity) of from about 0.28 percent to 0.34 percent.

More particularly, the polyetherester has a density of about 1.12 whenmeasured in accordance with ASTM D-792; a melt point of about 383° F.when measured in accordance with ASTM D-2117; a tensile strength ofabout 2,468 psi when measured in accordance with ASTM D-638, anelongation at break of about 650 percent when measured in accordancewith ASTM D-638 and a flexural modulus of about 7,258 psi when measuredin accordance with ASTM D-790.

The secondary fibers, which may be microfibers, may be selected from thegroup including polyester fibers, polyamide fibers, glass fibers,polyolefin fibers, cellulosic derived fibers, multi-component fibers,natural fibers or electrically conductive fibers or blends of two ormore of said secondary fibers. If the secondary fibers are naturalfibers, the natural fibers may be selected from the group includingcotton fibers, wool fibers and silk fibers. If the secondary fibers arepolyolefin fibers, the polyolefin fibers may be selected from the groupincluding polyethylene fibers or polypropylene fibers. If the secondaryfibers are cellulosic derived fibers, the cellulosic derived fibers maybe selected from the group including rayon fibers or wood fibers, forexample, wood pulp If the secondary fibers are polyamide fibers, thepolyamide fibers may be nylon fibers. If the secondary fibers aremulti-component fibers, the multi-component fibers may be sheath-corefibers or side-by-side fibers. The secondary fibers may be absorbent orsuperabsorbent fibers.

If secondary fibers are present in the nonwoven elastic web, thenonwoven elastic web may generally include from about 20 percent, byweight, to about 99 percent, by weight, of fibers formed from thepolyetherester material blended with from about 1 percent, by weight to80 percent, by weight, of the secondary fibers. For example, the elasticnonwoven web may include from about 50 percent, by weight to about 99percent, by weight, of fibers formed from the polyetherester blendedwith from about 1 percent, by weight, to about 50 percent, by weight, ofthe secondary fibers. More particularly, the elastic nonwoven web mayinclude from about 75 percent, by weight, to about 95 percent, byweight, of fibers formed from the polyetherester blended with from about5 percent, by weight, to about 25 percent, by weight, of the secondaryfibers. In certain applications, particulate materials may besubstituted for the secondary fibers or the elastic nonwoven web mayhave both secondary fibers and particulate materials incorporated intothe matrix of coherent polyetherester fibers. In such a three componentsystem, the elastic nonwoven web may contain from about 50 percent, byweight, to about 98 percent, by weight, of the polyetherester fibers,from about 1 percent, by weight, to about 49 percent, by weight, ofsecondary fibers and from about 1 percent, by weight, to about 49percent, by weight, of particulate materials. Exemplary particulatematerials are activated charcoal and powdered superabsorbent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an apparatus which may be utilizedto form the elastic nonwoven web of the present invention.

FIG. 2 is a bottom view of the die of FIG. 1 with the die having beenrotated 90 degrees for clarity.

FIG. 3 is a cross-sectional view of the die of FIG. 1 taken along line3--3 of FIG. 2.

FIG. 4 is a schematic illustration of an apparatus which may be utilizedto form the embodiment of the present invention where secondary fibersare incorporated into the matrix of coherent polyetherester fibers.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to the figures wherein like reference numerals represent thesame or equivalent structure and, in particular, to FIG. 1 where it canbe seen that an apparatus for forming the elastic nonwoven web of thepresent invention is schematically generally represented by referencenumeral 10. In forming the elastic nonwoven web of the present inventionpellets or chips, etc.(not shown) of a polyetherester material areintroduced into a pellet hopper 12 of an extruder 14.

One polyetherester may be obtained under the trade deshgnation Arnitel,for example, Arnitel EM-400, from A. Schulman, Inc. of Akron, Ohio orAkzo Plastics of Arnhem, Holland.

Schulman literature indicates that at least two grades of Arnitel areare available under the trade designations EM 400 and EM 460. Thisliterature also reports certain properties of these materials which aresummarized below in Table I.

                  TABLE I                                                         ______________________________________                                                                         MEASURED                                                                      BY ASTM                                      PROPERTY       EM-400   EM-460   STANDARD                                     ______________________________________                                        Density        1.12     1.16     D-792                                        Melt Point                                                                    (deg. F.)      383      365      D-2117                                       (deg. C.)      195      185                                                   Water absorption at                                                                          0.32     0.30     D-570                                        equilibrium at RT and                                                         50% RH (%)                                                                    Tensile strength (psi)                                                                       2,468    3,048    D-638                                        Elongation at break (%)                                                                      650      700      D-638                                        Flexural Modulus (psi)                                                                       7,258    14,516   D-790                                        ______________________________________                                    

From the table, above, it can be seen that these Arnitel polyetherestermaterials have a density of from about 1.10 to about 1.18 when measuredin accordance with ASTM D-792; a melt point of from about 350° F. toabout 400° F. when measured in accordance with ASTM D-2117; a waterabsorption at equilibrium, room temperature and 50 percent relativehumidity of from about 0.28 percent to about 0.34 percent; a tensilestrength of from about 2,250 psi to about 3,250 psi when measured inaccordance with ASTM D-638; an elongation at break of from about 600percent to about 750 percent when measured in accordance with ASTM D-638and a flexural modulus of from about 6,500 psi to about 15,000 psi whenmeasured in accordance with ASTM . D-790.

More particularly, the Arnitel EM-400 polyetherester has a density ofabout 1.12 when measured in accordance with ASTM D-792; a melt point ofabout 383° F. when measured in accordance with ASTM D-2117; a waterabsorption of about 0.32 percent at equilibrium, room temperature and 50percent relative humidity; a tensile strength of about 2,468 psi whenmeasured in accordance with ASTM D-638, an elongation at break of about650 percent when measured in accordance with ASTM D-638 and a flexuralmodulus of about 7,258 psi when measured in accordance with ASTM D-790.

The polyetherester may be mixed with other appropriate materials, suchas, for example, pigments, anti-oxidants, stabilizers, waxes, flowpromoters, solid solvents, particulates and processing enhancingadditives, prior to or after its introduction into the hopper 12.

The extruder 14 has an extrusion screw (not shown) which is driven by aconventional drive motor (not shown). As the polyetherester advancesthrough the extruder 14, due to rotation of the extrusion screw by thedrive motor, it is progressively heated to a molten state. Heating ofthe polyetherester to the molten state may be accomplished in aplurality of discrete steps with its temperature being graduallyelevated as it advances through discrete heating zones of the extruder14 toward a meltblowing die 16. The die 16 may be yet another heatingzone where the temperature of the thermoplastic resin is maintained atan elevated level for extrusion. The temperature which will be requiredto heat the polyetherester to a molten state will vary somewhatdepending upon which grade of polyetherester is utilized and can bereadily determined by those in the art. However, generally speaking, theArnitel polyetherester may be extruded within the temperature range offrom about 176 degrees Centigrade to about 300 degrees Centigrade. Forexample, the extrusion may be accomplished within a temperature range offrom about 185 degrees. Centigrade to about 282 degrees Centigrade.Heating of the various zones of the extruder 14 and the meltblowing die16 may be achieved by any of a variety of conventional heatingarrangements (not shown).

FIG. 2 illustrates that the lateral extent 18 of the die 16 is providedwith a plurality of orifices 20 which are usually circular incross-section and are linearly arranged along the extent 18 of the tip22 of the die 16. The orifices 20 of the die 16 may have diameters thatrange from about 0.01 of an inch to about 0.02 of an inch and a lengthwhich may range from about 0.05 inches to about 0.20 inches. Forexample, the orifices may have a diameter of about 0.0145 inches and alength of about 0.113 inches. From about 5 to about 50 orifices may beprovided per inch of the lateral extent 18 of the tip 22 of the die 16with the die 16 extending from about 30 inches to about 60 inches ormore. FIG. 1 illustrates that the molten polyetherester emerges from theorifices 20 of the die 16 as molten strands or threads 24.

FIG. 3, which is a cross-sectional view of the die of FIG. 2 taken alongline 3--3, illustrates that the die 16 preferably includes attenuatinggas inlets 26 and 28 which are provided with heated, pressurizedattenuating gas (not shown) by attenuating gas sources 30 and 32. (SeeFIGS. 1 and 2.) The heated, pressurized attenuating gas enters the die16 at the inlets 26 and 28 and follows a path generally designated bythe arrows 34 and 36 through the two chambers 38 and 40 and on throughthe two narrow passageways or gaps 42 and 44 so as to contact theextruded threads 24 as they exit the orifices 20 of the die 16. Thechambers 38 and 40 are designed so that the heated attenuating gaspasses through the chambers 38 and 40 and exits the gaps 42 and 44 toform a stream (not shown) of attenuating gas which exits the die 16 onboth sides of the threads 24. The temperature and pressure of the heatedstream of attenuating gas can vary widely. For example, the heatedattenuating gas can be applied at a temperature of from about 245degrees Centigrade to about 304 degrees Centigrade, more particularly,from about 260 degrees Centigrade to about 300 degrees Centigrade. Theheated attenuating gas may generally be applied at a pressure of fromabout 0.5 pounds per square inch, gage to about 20 pounds per squareinch, gage. More particularly, from about 1 pound per square inch, gageto about 5 pounds per square inch, gage.

The position of air plates 46 and 48 which, in conjunction with a dieportion 50 define the chambers 38 and 40 and the gaps 42 and 44, may beadjusted relative to the die portion 50 to increase or decrease thewidth of the attenuating gas passageways 42 and 44 so that the volume ofattenuating gas passing through the air passageways 42 and 44 during agiven time period can be varied without varying the velocity of theattenuating gas. Furthermore, the air plates 46 and 48 may be adjustedto effect a "recessed" die-tip configuration as illustrated in FIG. 3 ora positive die-tip 22 stick-out where the tip of die portion 50protrudes beyond the plane formed by the plates 48. Generally speaking,a positive die-tip stick-out configuration and attenuating gas pressuresof less than 5 pounds per square inch, gage are used in conjunction withair passageway widths, which are usually the same and are no greater inwidth than about 0.110 inches. Lower attenuating gas velocities andwider air passageway gaps are generally preferred if substantiallycontinuous meltblown fibers or microfibers 24 are to be produced.

The two streams of attenuating gas converge to form a stream of gaswhich entrains and attenuates the molten threads 24, as they exit theorifices 20, into fibers or, depending upon the degree of attenuation,microfibers, cf a small diameter which is usually less than the diameterof the orifices 20. The gas-borne fibers or microfibers 24 are blown, bythe action of the attenuating gas, onto a collecting arrangement which,in the embodiment illustrated in FIG. 1, is a foraminous endless belt 52conventionally driven by rollers 54. Other foraminous arrangements suchas a rotating drum could be utilized. One or more vacuum boxes (notillustrated) may be located below the surface of the foraminous belt 52and between the rollers 54. The fibers or microfibers 24 are collectedas a coherent matrix of fibers on the surface of the endless belt 52which is rotating as indicated by the arrow 58 in FIG. 1. The vacuumboxes assist in retention of the matrix on the surface of the belt 52.Typically the tip 22 of the die 16 is from about 6 inches to about 14inches from the surface of the foraminous belt 52 upon which the fibersare collected. The thus-collected, entangled fibers or microfibers 24are coherent and may be removed from the belt 52 as a self-supportingnonwoven web 56 by a pair of pinch rollers 60 and 62 which may bedesigned to press the fibers of the web 56 together to improve theintegrity of the web 56.

FIG. 4 illustrates another embodiment of the present invention where oneor more types of secondary fibers 64 are distributed within or upon thestream of thermoplastic fibers or microfibers 24. Distribution of thesecondary fibers 64 within the stream of fibers 24 may be such that thesecondary fibers 64 are generally uniformly distributed throughout thestream of polyetherester fibers 24. This may be accomplished by merginga secondary gas stream (not shown) containing the secondary fibers 64with the stream of fibers 24. Apparatus for accomplishing this mergermay include a conventional picker roll 66 arrangement which has aplurality of teeth 68 that are adapted to separate a mat or batt 70 ofsecondary fibers into the individual secondary fibers 64. The mat orbatt of secondary fibers 70 which is fed to the picker roll 66 may be asheet of pulp fibers (if a two component mixture of polyetheresterfibers and secondary pulp fibers is desired), a mat of. staple fibers(if a two component mixture of polyetherester fibers and secondarystaple fibers is desired) or both a sheet of pulp fibers and a mat ofstaple fibers (if a three component mixture of polyetherester fibers,secondary staple fibers and secondary pulp fibers is desired). Inembodiments where, for example, an absorbent material is desired, thesecondary fibers 64 are absorbent fibers. The secondary fibers 64 maygenerally be selected from the group including one or more polyesterfibers, polyamide fibers, polyolefin fibers such as, for example,polyethylene fibers and polypropylene fibers, cellulosic derived fiberssuch as, for example, rayon fibers and wood pulp fibers, multi-componentfibers such as, for example, sheath-core multi-component fibers orside-by-side multi-component fibers, natural fibers such as silk fibers,wool fibers or cotton fibers or electrically conductive fibers or blendsof two or more of such secondary fibers. Other types of secondary fibers64 as well as blends of two or more of other types of secondary fibers64 may be utilized. The secondary fibers 64 may be microfibers or thesecondary fibers 64 may be macrofibers having an average diameter offrom about 300 microns to about 1,000 microns.

The sheets or mats 70 of secondary fibers 64 are fed to the picker roll66 by a roller arrangement 72. After the teeth 68 of the picker roll 66have separated the mat of secondary fibers 70 into separate secondaryfibers 64 the individual secondary fibers 64 are conveyed toward thestream of polyetherester fibers or microfibers 24 through a nozzle 74. Ahousing 76 encloses the picker roll 66 and provides a passageway or gap78 between the housing 76 and the surface of the teeth 68 of the pickerroll 66. A gas (not shown), for example air, is supplied to thepassageway or gap 78 between the surface of the picker roll 66 and thehousing 76 by way of a gas duct 80. The gas duct 80 may enter thepassageway or gap 78 generally at the junction 82 of the nozzle 74 andthe gap 78. The gas is supplied in sufficient quantity to serve as amedium for conveying the secondary fibers 64 through the nozzle 74. Thegas supplied from the duct 80 also serves as an aid in removing thesecondary fibers 64 from the teeth 68 of the picker roll 66. However,gas supplied through the duct 84 generally provides for the removal ofthe secondary fibers 64 from the teeth of the picker roll 66. The gasmay be supplied by any conventional arrangement such as, for example, anair blower (not shown).

Generally speaking, the individual secondary fibers 64 are conveyedthrough the nozzle 74 at generally the velocity at which the secondaryfibers 64 leave the teeth 68 of the picker roll 66. In other words, thesecondary fibers 64, upon leaving the teeth 68 of the picker roll 66 andentering the nozzle 74, generally maintain their velocity in bothmagnitude and direction from the point where they left the teeth 68 ofthe picker roll 66. Such an arrangement, which is discussed in moredetail in U.S. Pat. No. 4,100,324 to Anderson et al., herebyincorporated by reference, aids in substantially reducing fiberfloccing.

As an aid in maintaining satisfactory secondary fiber 64 velocity, thenozzle 74 may be positioned so that its longitudinal axis issubstantially parallel to a plane which is tangent to the picker roll 66at the junction 82 of the nozzle 74 with the passageway 78. As a resultof this configuration, the velocity of the secondary fibers 64 is notsubstantially changed by contact of the secondary fibers 64 with thewalls of the nozzle 74. If the secondary fibers 64 temporarily remain incontact with the teeth 68 of the picker roll 66 after they have beenseparated from the mat or batt 70, the axis of the nozzle 74 may beadjusted appropriately to be aligned with the direction of secondaryfiber 64 velocity at the point where the secondary fibers 64 disengagefrom the teeth 68 of the picker roll 66. The disengagement of thesecondary fibers 64 from the teeth 68 of the picker roll 66 may beassisted by application of a pressurized gas, i.e., air through duct 84.

The vertical distance 86 that the nozzle 74 is below the die tip 22 maybe adjusted to vary the properties of the composite web 88. Variation ofthe horizontal distance 90 of the tip 92 of the nozzle 74 from the dietip 24 will also achieve variations in the final elastic nonwoven web88. The vertical distance 86 and the horizontal distance 90 values willalso vary with the material being added to the polyetherester fibers 24.The width of the nozzle 74 along the picker roll 66 and the length thatthe nozzle 74 extends from the picker roll 66 are also important inobtaining optimum distribution of the secondary fibers 64 throughout thestream of fibers 24. It is usually desirable for the length of thenozzle 74 to be as short as equipment design will allow. The length isusually limited to a minimum length which is generally equal to theradius of the picker roll 66. Usually, the width of the nozzle 74 shouldnot exceed the width of the sheets or mats 70 that are being fed to thepicker roll 66.

The picker roll 66 may be replaced by a conventional particulateinjection system to form a composite nonwoven web 88 containing varioussecondary particulates. A combination of both secondary particulates andsecondary fibers could be added to the polyetherester fibers prior toformation of the composite nonwoven web 88 if a conventional particulateinjection system was added to the system illustrated in FIG. 4.

FIG. 4 further illustrates that the gas stream carrying the secondaryfibers 64 is moving in a direction which is generally perpendicular tothe direction of movement of the stream of polyetherester fibers 24 atthe point of merger of the two streams. Other angles of merger of thetwo streams may be utilized. The velocity of the gas stream of secondaryfibers 64 is usually adjusted so that it is less than the velocity ofthe stream of polyetherester fibers 24. This allows the streams, uponmerger and integration thereof to flow in substantially the samedirection as that of the stream of polyetherester fibers 24. Indeed, themerger of the two streams may be accomplished in a manner which issomewhat like an aspirating effect where the stream of secondary fibers64 is drawn into the stream of polyetherester fibers 24. If desired thevelocity difference between the two gas streams may be such that thesecondary fibers 64 are integrated into the polyetherester fibers 24 ina turbulent manner so that the secondary fibers 64 become substantiallythoroughly and uniformly mixed throughout the polyetherester fibers 24.Generally, for increased production rates the gas stream which entrainsand attenuates the stream of polyetherester fibers 24 should have acomparatively high initial velocity, for example from about 200 feet toover 1,000 feet per second, and the stream of gas which carries thesecondary fibers 64 should have a comparatively low initial velocity,for example from about 50 to about 200 feet per second. After the streamof gas that entrains and attenuates the polyetherester fibers 24 exitsthe gaps 42 and 44 of the die 16, it immediately expands and decreasesin velocity.

Upon merger and integration of the stream of secondary fibers 64 intothe stream of polyetherester fibers 24 to generally uniformly distributethe secondary fibers 64 throughout the stream of polyetherester fibers24, a composite stream 96 of thermoplastic fibers 24 and secondaryfibers 64 is formed. Due to the fact that the polyetherester fibers 24are usually still semi-molten and tacky at the time of incorporation ofthe secondary fibers 64 into the polyetherester fibers 24, the secondaryfibers 64 are usually not only mechanically entangled within the matrixformed by the polyetherester fibers 24 but are also thermally bonded orjoined to the polyetherester fibers 24.

In order to convert the composite stream 96 of polyetherester fibers 24and secondary fibers 64 into a composite elastic nonwoven web or mat 88composed of a coherent matrix of the polyetherester fibers 24 having thesecondary fibers 64 generally uniformly distributed therein, acollecting device is located in the path of the composite stream 96. Thecollecting device may be the endless belt 52 of FIG. 1 upon which thecomposite stream 96 impacts to form the composite nonwoven web 56. Thebelt 52 is usually porous and a conventional vacuum arrangement (notshown) which assists in retaining the composite stream 96 on theexternal surface of the belt 52 is usually present. Other collectingdevices are well known to those of skill in the art and may be utilizedin place of the endless belt 52. For example, a porous rotating drumarrangement could be utilized. Thereafter, the composite elasticnonwoven web 88 is removed from the screen by the action of rollers suchas roller 60 and 62 shown in FIG. 1.

EXAMPLE I

A fibrous nonwoven elastic web was formed by meltblowing apolyetherester obtained from Akzo Plastics under the trade designationArnitel EM 400.

Meltblowing of the Arnitel EM 400 was accomplished by extruding thethermoplastic elastomer through a 11/2 inch diameter Johnson extruderand through a meltblowing die having 30 extrusion capillaries per linealinch of die tip. The capillaries each had a diameter of about 0.0145inches and a length of about 0.113 inches. The Arnitel EM 400 wasextruded through the capillaries at a rate of about 0.1513 grams percapillary per minute at a temperature of about 272 degrees Centigrade.The extrusion pressure exerted upon the Arnitel EM 400 in the die tipwas measured as 196 pounds per square inch, gage. The die tipconfiguration was adjusted so that it had a positive die tip stickout ofabout 0.010 inches from the plane of the external surface of the lips ofthe air plates which form the air passageways on either side of thecapillaries. The air plates were adjusted so that the two airpassageways, one on each side of the extrusion capillaries, formed airpassageways of a width or gap of about 0.067 inches. Forming air formeltblowing the Arnitel EM 400 was supplied to the air passageways at atemperature of about 284 degrees Centigrade and at a pressure of about 3pounds per square inch, gage. The viscosity of the Arnitel EM 400 wascalculated at 653 poise in the capillaries. The meltblown fibers thusformed were blown onto a forming screen which was approximately 14inches from the die tip.

Examples 2-7 were conducted in the fashion stated with regard toExample 1. All of the examples were performed with Arnitel EM 400 on a11/2 inch diameter Johnson extruder and with a meltblowing die which had30 extrusion capillaries per lineal inch of die tip. The capillaries ofthe meltblowing die each had a diameter of about 0.0145 inches and alength of about 0.113 inches. The various process parameters of Examples2-7 are detailed in Table II.

                                      TABLE II                                    __________________________________________________________________________    Example  2    3    4    5    6    7                                           __________________________________________________________________________    Extrusion Rate.sup.1                                                                   0.1513                                                                             0.1513                                                                             0.1513                                                                             0.1513                                                                             0.2522                                                                             0.2522                                      Extrusion Die                                                                          272  272  272  272  282  283                                         Temperature.sup.2                                                             Extrusion Die                                                                          183  180  170  187  200  196                                         Pressure.sup.3                                                                Die Tip  0.010                                                                              0.010                                                                              0.010                                                                              0.010                                                                              0.010                                                                              0.010                                       Stick-Out.sup.4                                                               Air      0.067                                                                              0.067                                                                              0.067                                                                              0.067                                                                              0.067                                                                              0.067                                       Passageway Gap.sup.5                                                          Air Temperature.sup.6                                                                  284  284  284  284  296  296                                         Air Pressure.sup.7                                                                     3    1    1    1    3    3                                           Material 610  605  567  623  400  392                                         Viscosity.sup.8                                                               Distance.sup.9                                                                         14   14   14   14   14   14                                          Die-Tip to                                                                    Forming Screen                                                                __________________________________________________________________________     The following footnotes apply to Table II:                                    .sup.1 in grams per capillary per minute                                      .sup.2 in degrees Centigrade                                                  .sup.3 in pounds per square inch, gage in the capillaries                     .sup.4 negative values indicate recessed die tip arrangement, in inches       .sup.5 in inches                                                              .sup.6 in degrees Centigrade                                                  .sup.7 in pounds per square inch, gage                                        .sup.8 in poise                                                               .sup.9 in inches                                                         

TENSILE AND CYCLING DATA EXAMPLES 1-7

The resulting meltblown fabrics were tested on an Instron tensiletester. Samples are cut to 3" width by 7" length, with the 7" dimensionin the direction of stretch measurement. Five samples are cut for eachfabric direction measured (machine direction and cross machinedirection). The sample is placed lengthwise in jaw faces, 3" wide×1"length, with a jaw span or separation of 4 inches. The Instron crossheadspeed is set at 20 inches per minute. The peak and break elongation andthe peak load were recorded and are presented in Table III.

The extension and load values may be varied over a wide range as neededby varying the process conditions accordingly. (See Examples 1-7.) Thevalues reported in Table III are average values for five replicatetests. The figure in parenthesis represents the coefficient of variationof the five test values from the average value reported.

Stress-relaxation cycling tests for samples 1 and 4 were conducted.These tests require that the sample of elastomeric fabric be cycled from0% to X% elongation and then returned to a relaxed state. X% elongationis 75% of the peak elongation as determined from the tensile data. Afterthe fifth extension, the fabric is elongated one final time to break.Examples 1 and 4 reveal that the elastic fabric achieves about the samepeak load on successive stretches to the same predetermined elongation.

                                      TABLE III*                                  __________________________________________________________________________            Peak      Peak       Break             Cycle Cycle                    Basis   Elongation (%)                                                                          Load (LB)  Elongation (%)                                                                              Cycle                                                                             Elong (%)                                                                           Peak Load (LB)           Ex                                                                              Wt. (gsm)                                                                           MD   CD   MD   CD    MD   CD       No. MD CD MD   CD                  __________________________________________________________________________    1 63.1   71(.12)                                                                           388(.14)                                                                           4.51(.07)                                                                          6.24(.16)                                                                           126(.20)                                                                           405(.14) 1    55                                                                              300                                                                              5.06(.07)                                                                          5.89(.09)                                                      2    55                                                                              300                                                                              4.74(.07)                                                                          5.46(.09)                                                      3    55                                                                              300                                                                              4.56(.07)                                                                          5.24(.09)                                                      4    55                                                                              300                                                                              4.45(.07)                                                                          5.08(.10)                                                      5    55                                                                              300                                                                              4.37(.07)                                                                          4.97(.10)           2 116.7  69(.12)                                                                           515(.03)                                                                           5.78(.07)                                                                          11.40(.04)                                                                          137(.35)                                                                           532(.03)                                    3 46.5  277(.10)                                                                           630(.06)                                                                           2.91(.08)                                                                          3.42(.08)                                                                           369(.10)                                                                           Did Not Break**                             4 86.3  316(.09)                                                                           601(.00)                                                                           6.70(.04)                                                                          5.90(.02)                                                                           359(.10)                                                                           Did Not Break**                                                                        1   225                                                                              450                                                                              5.93(.03)                                                                          4.73(.03)                                                      2   225                                                                              450                                                                              5.67(.03)                                                                          4.48(.03)                                                      3   225                                                                              450                                                                              5.49(.03)                                                                          4.32(.03)                                                      4   225                                                                              450                                                                              5.37(.04)                                                                          4.21(.03)                                                      5   225                                                                              450                                                                              5.28(.04)                                                                          4.14(.03)           5 109.3 328(.05)                                                                           611(.08)                                                                           7.50(.06)                                                                          7.62(.06)                                                                           326(.05)                                                                           Did Not Break**                             6 56.6  592(.04)                                                                           602(.03)                                                                           6.38(.11)                                                                          4.96(.02)                                                                           569(.00)                                                                           600(.00)                                    7 100.4 555(.07)                                                                           600(.00)                                                                           9.51(.17)                                                                          8.62(.03)                                                                           572(.00)                                                                           Did Not Break**                             __________________________________________________________________________     *Data Not Normalized                                                          **Sample did not break at the maximum extension capability of the machine     (About 600%)                                                             

While the present invention has been described in connection withcertain preferred embodiments, it is to be understood that the subjectmatter encompassed by way of the present invention is not to be limitedto those specific embodiments. On the contrary, it is intended for thesubject matter of the invention to include all alternatives,modifications and equivalents as can be included within the spirit andscope of the following claims.

What is claimed is:
 1. Elastic meltblown microfibers comprising:apolyetherester material having the general formula of: ##STR3## where"G" is selected from the group consisting of:poly(oxyethylene)-alpha,omega-diol poly(oxypropylene)-alpha,omega-diolpoly(oxytetramethylene)-alpha,omega-diol and"a", "m" and "n" arepositive integers; and wherein said material has an elongation at breakof from about 600 percent to 750 percent when measured in accordancewith ASTM D-638 and a melt point of from about 350° F. to about 400° F.when measured in accordance with ASTM D-2117.
 2. The elastic meltblownfibers of claim 1 wherein "a" is selected from the group consisting of2, 4 or
 6. 3. The elastic meltblown fiber of claim 1 wherein said fibersare microfibers.
 4. The elastic meltblown microfibers of claim 1,wherein said material has a density of from about 1.10 to about 1.18when measured in accordance with ASTM D-792.
 5. Elastic meltblownmicrofibers consisting essentially of:a polyetherester material havingthe general formula ##STR4## where: "G" is selected from the groupconsisting of: poly(oxyethylene)-alpha,omega-diolpoly(oxypropylene)-alpha,omega-diolpoly(oxytetramethylene)-alpha,omega-diol and"a", "m" and "n" arepositive integers; and wherein said material has an elongation at breakof from about 600 percent to 750 percent when measured in accordancewith ASTM D-638 and a melt point of from about 350° F. to about 400° F.when measured in accordance with ASTM D-2117.
 6. An elastic nonwoven webcomprising:a coherent matrix of fibers formed from a polyetherestermaterial having the general formula of: ##STR5## where: "G" is selectedfrom the group consisting of: poly(oxyethylene)-alpha,omega-diolpoly(oxypropylene)-alpha,omega-diolpoly(oxytetramethylene)-alpha,omega-diol and"a", "m" and "n" arepositive integers; and wherein said material has an elongation at breakof from about 600 percent to 750percent when measured in accordance withASTM D-638 and a melt point of from about 350° F. to about 400° F. whenmeasured in accordance with ASTM D-2117.
 7. The elastic nonwoven web ofclaim 6, wherein "a" is selected from the group consisting of 2, 4 or 6.8. The elastic nonwoven web of claim 6, wherein said fibers aremicrofibers.
 9. The elastic nonwoven web of claim 6, wherein saidmaterial has a density of from about 1.10 to about 1.18 when measured inaccordance with ASTM D-792.
 10. An elastic nonwoven web consistingessentially of:a coherent matrix of fibers formed from a polyetherestermaterial having the general formula of: ##STR6## where: "G" selectedfrom the group consisting of: poly(oxyethylene)-alpha,omega-diolpoly(oxypropylene)-alpha,omega-diolpoly(oxytetramethylene)-alpha,omega-diol and"a", "m" and "n" arepositive integers; and wherein said material has an elongation at breakof from about 600 percent to 750 percent when measured in accordancewith ASTM D-638 and a melt point of from about 350° F. to about 400° F.when measured in accordance with ASTM D-2117.
 11. An elastic nonwovenweb comprising:a coherent matrix of fibers formed from a polyetherestermaterial having the general formula of: ##STR7## where: "G" is selectedfrom the group consisting of: poly(oxyethylene)-alpha,omega-diolpoly(oxypropylene)-alpha,omega-diolpoly(oxytetramethylene)-alpha,omega-diol and"a", "m" and "n" arepositive integers; and wherein said material has an elongation at breakof from about 600 percent to 750 percent when measured in accordancewith ASTM D-638 and a melt point of from about 350° F. to about 400° F.when measured in accordance with ASTM D-2117; and nonelastic secondaryfibers.
 12. The elastic nonwoven web of claim 11, wherein "a" isselected from the group consisting of 2, 4 or
 6. 13. The elasticnonwoven web of claim 11, wherein said fibers are microfibers.
 14. Theelastic nonwoven web of claim 11, wherein said material has a density offrom about 1.10 to about 1.18 when measured in accordance with ASTMD-792.
 15. The elastic nonwoven web of claim 11, comprising from about 1percent, by weight, to about 80 percent, by weight, of said secondaryfibers.
 16. The elastic nonwoven web of claim 11 comprising from about 1percent, by weight, by about 50 percent, by weight, of said secondaryfibers.
 17. The elastic nonwoven web of claim 11 comprising from about 5percent, by weight, to about 25 percent, by weight, of said secondaryfibers.
 18. The elastic nonwoven web of claim 11 comprising from about 1percent, by weight, to about 49 percent, by weight, of said secondaryfibers and from about 1 percent, by weight, to about 49 percent, byweight, of a particulate material.
 19. The elastic nonwoven web of claim11, wherein said secondary fibers are selected from the group consistingof polyester fibers, polyamide fibers, glass fibers, polyolefin fibers,cellulosic derived fibers, multi-component fibers, natural fibers,absorbent fibers, electrically conductive fibers or blends of two ormore of said secondary fibers.
 20. The elastic nonwoven web of claim 19,wherein said natural fibers are selected from the group consisting ofcotton fibers, wool fibers or silk fibers.
 21. The elastic nonwoven webof claim 19, wherein said polyolefin fibers are selected from the groupconsisting of polyethylene fibers or polypropylene fibers.
 22. Theelastic nonwoven web of claim 19, wherein said cellulosic derived fibersare selected from the group consisting of rayon fibers or wood fibers.23. The elastic nonwoven web of claim 19, wherein said polyamide fibersare nylon fibers.
 24. The elastic nonwoven web of claim 19, wherein saidmulti component fibers are selected from the group consisting ofsheath-core or side-by-side fibers.
 25. An elastic nonwoven webconsisting essentially of:a coherent matrix of fibers formed from apolyetherester material having the general formula of: ##STR8## where: Gis selected from the group consisting of:poly(oxyethylene)-alpha,omega-diol poly(oxypropylene)-alpha,omega-diolpoly(oxytetramethylene)-alpha,omega-diol anda, m and n are positiveintegers; and wherein said material has an elongation at break of fromabout 600 percent to 750 percent when measured in accordance with ASTMD-638 and a melt point of from about 350° F. to about 400° F. whenmeasured in accordance with ASTM D-2117; and nonelastic secondaryfibers.
 26. An elastic nonwoven web comprising:a coherent matrix offibers formed from a polyetherester material having the general formulaof: ##STR9## where: "G" is selected from the group consisting of:poly(oxyethylene)-alpha,omega-diol poly(oxypropylene)-alpha,omega-diolpoly(oxytetramethylene)-alpha,omega-diol and"a", "m" and "n" arepositive integers; and wherein said material has an elongation at breakof from about 600 percent to 750 percent when measured in accordancewith ASTM D-638 and a melt point of from about 350° F. to about 400° F.when measured in accordance with ASTM D-2117; and particulate materials.